Pan Size Converter

How to Use This Converter

Pick your original pan shape and size, then enter the new pan you want to use. The calculator figures out the scaling factor based on surface area. Use the presets or quick conversion buttons to save time.

Pan dimensions are always measured on the inside, from one inner edge to the other—not including the rim.

Why Area Matters More Than Diameter

Pan conversion is about surface area, not diameter. When batter spreads across a pan, the area determines thickness. A 9" round pan has about 63.6 square inches of surface area (πr²). An 8" square pan has 64 square inches. That's why they're interchangeable—nearly identical area means nearly identical batter thickness.

The math isn't intuitive. Doubling a pan's diameter quadruples its area. Going from 8" to 10" round increases area by 56%, so you'd need to scale up your recipe by more than half just to keep the same thickness.

Round vs Square vs Rectangular

Round pans heat most evenly—heat travels equal distances from edges to center. Square and rectangular pans have corners where batter gets hit with heat from two sides, producing crunchier corner pieces. A 9×13" rectangular pan holds about the same as two 9" round pans, which is why most people use it for turning layer cakes into sheet cakes.

The Scaling Factor

Divide the new pan's area by the original pan's area. That's your scaling factor. A 9" round (63.6 sq in) to a 6" round (28.3 sq in) gives you 28.3 ÷ 63.6 = 0.44. Use 44% of each ingredient.

Baking Time Changes

Thicker batter takes longer. Thinner batter cooks faster. Rough rule: cut time by 15% when the surface area doubles, add 20% when it halves. Test for doneness instead of relying only on the timer.

Pan Materials

• Light aluminum: Even heating, pale crust, good for delicate cakes
• Dark/nonstick: Absorbs heat fast, darker crust—reduce temp 25°F
• Glass: Poor conductor but holds heat, reduce temp 25°F
• Silicone: Insulates batter, needs longer bake time, minimal browning

Bundt and Tube Pans

These are rated by cup capacity because their shapes make area calculations pointless. A 10-cup Bundt holds about the same as a 9×13" pan. A 12-cup Bundt matches two 9" round layers.

Cupcake Yields

Standard cupcakes take about 3 tablespoons of batter each (filled two-thirds). A 9" round recipe makes about 24. Minis need 1 tablespoon and yield 48-60. Jumbos take half a cup and produce 8-10. Check them a few minutes early—small portions overbake fast.

How Much to Fill

• Cakes: ⅔ full—leaves room to rise
• Cheesecakes: Can fill higher since they barely rise
• Brownies/bars: ¾ full is fine—dense batters do not climb

Before You Swap Pans

Test the volume first. Fill the new pan with water and measure. If your calculated scaling factor is between 0.9 and 1.1, you can usually skip the math and just use the recipe as-is.

Some things should not be swapped. Angel food needs the tube for structure. Cheesecake needs the springform for extraction. When in doubt, a slightly larger pan is usually safer than one that is too small.

Using Pan Size Math With Recipe Scaling

Pan conversion is closely tied to ingredient scaling. If the new pan area is 25% larger, the batter usually needs to increase by about 25% to keep the same depth. If the new pan is smaller, reducing the recipe helps prevent overflow and dense centers.

Area First, Volume Second

Area controls batter thickness for most cakes, bars, brownies, and sheet-pan bakes. Volume becomes more important for deep pans, loaf pans, Bundt pans, and tube pans where capacity can limit how much batter fits safely.

Scale Ingredients After Choosing the Pan

After the pan scaling factor is known, the recipe scaler can adjust the ingredient list. For batters that depend on exact flour or sugar amounts, convert cups to grams first with the ingredient weight converter.

Watch Temperature and Doneness

Pan material changes heat transfer. Dark metal, glass, and silicone can all shift baking time. Use the cooking temperature converter when switching between Fahrenheit, Celsius, and Gas Mark recipes.

Keeping batter depth comparable

Surface-area scaling works best when the original and replacement pans have similar usable depth. After multiplying the ingredients, compare the expected batter depth rather than filling solely to the rim. A shallow layer sets and browns sooner; a deeper layer can look finished at the edge while its center still needs time. Leave the headroom required for the batter's normal rise, especially with foam cakes and strongly leavened batters.

Pan dimensions should be measured inside the vessel. Rolled rims, handles, and outside measurements do not hold batter. For tapered loaf pans or decorative molds, a water-capacity test is often more useful than multiplying length by width. Measure the water used, dry the pan completely, and compare that usable capacity with the original vessel before committing a full recipe.

Checking doneness after a pan swap

Keep the original oven temperature unless the recipe or pan material calls for a change, but start checking earlier when batter is spread thinner. Use the test appropriate to the bake: center temperature, a clean skewer, spring-back, edge set, or another recipe-specific cue. The converter estimates ingredient scale; it cannot predict the exact minute at which a different pan and oven will finish the bake.